There is a known technology in which a synthetic-resin splash guard, which covers an engine of an automobile from the side and the below so as to protect auxiliary equipment from a spray of water, has six triangle-shaped elastic flat pieces separated by six radially extending slits formed therein such that an opening is formed by pressing the elastic flat pieces so as to allow a tool to be inserted therethrough for maintenance of auxiliary equipment. This technology has been disclosed in Japanese Examined Utility Model Registration Application Publication No. 7-28060, the entire contents of which are incorporated herein by reference.